mst is right: there is no sane way to allow automatic inflation with HRI, as most...

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / ResultClass / HashRefInflator.pm

diff --git a/lib/DBIx/Class/ResultClass/HashRefInflator.pm b/lib/DBIx/Class/ResultClass/HashRefInflator.pm
index fc0ee37..5fffad4 100644 (file)
--- a/lib/DBIx/Class/ResultClass/HashRefInflator.pm
+++ b/lib/DBIx/Class/ResultClass/HashRefInflator.pm
@@ -9,17 +9,23 @@ DBIx::Class::ResultClass::HashRefInflator
 
 =head1 SYNOPSIS
 
- my $rs = $schema->resultset('CD');
+ use DBIx::Class::ResultClass::HashRefInflator;
 
+ my $rs = $schema->resultset('CD');
  $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
+ while (my $hashref = $rs->next) {
+    ...
+ }
 
 =head1 DESCRIPTION
 
-DBIx::Class is not built for speed: it's built for convenience and
-ease of use. But sometimes you just need to get the data, and skip the
-fancy objects. That is what this class provides.
+DBIx::Class is faster than older ORMs like Class::DBI but it still isn't 
+designed primarily for speed. Sometimes you need to quickly retrieve the data
+from a massive resultset, while skipping the creation of fancy row objects.
+Specifying this class as a C<result_class> for a resultset will change C<< $rs->next >>
+to return a plain data hash-ref (or a list of such hash-refs if C<< $rs->all >> is used).
 
-There are two ways of using this class.
+There are two ways of applying this class to a resultset:
 
 =over
 
@@ -36,58 +42,66 @@ recommended.
 
 =back
 
+=cut
+
+##############
+# NOTE
+#
+# Generally people use this to gain as much speed as possible. If a new &mk_hash is
+# implemented, it should be benchmarked using the maint/benchmark_hashrefinflator.pl
+# script (in addition to passing all tests of course :). Additional instructions are
+# provided in the script itself.
+#
+
+# This coderef is a simple recursive function
+# Arguments: ($me, $prefetch) from inflate_result() below
+my $mk_hash;
+$mk_hash = sub {
+    if (ref $_[0] eq 'ARRAY') {     # multi relationship
+        return [ map { $mk_hash->(@$_) || () } (@_) ];
+    }
+    else {
+        my $hash = {
+            # the main hash could be an undef if we are processing a skipped-over join
+            $_[0] ? %{$_[0]} : (),
+
+            # the second arg is a hash of arrays for each prefetched relation
+            map
+                { $_ => $mk_hash->( @{$_[1]->{$_}} ) }
+                ( $_[1] ? (keys %{$_[1]}) : () )
+        };
+
+        # if there is at least one defined column consider the resultset real
+        # (and not an emtpy has_many rel containing one empty hashref)
+        for (values %$hash) {
+            return $hash if defined $_;
+        }
+
+        return undef;
+    }
+};
+
 =head1 METHODS
 
 =head2 inflate_result
 
-Inflates the result and prefetched data into a hash-ref using L<mk_hash>.
+Inflates the result and prefetched data into a hash-ref (invoked by L<DBIx::Class::ResultSet>)
 
 =cut
 
+##################################################################################
+# inflate_result is invoked as:
+# HRI->inflate_result ($resultsource_instance, $main_data_hashref, $prefetch_data_hashref)
 sub inflate_result {
-    my ($self, $source, $me, $prefetch) = @_;
-
-    return mk_hash($me, $prefetch);
+    return $mk_hash->($_[2], $_[3]);
 }
 
-=head2 mk_hash
-
-This does all the work of inflating the (pre)fetched data.
 
-=cut
+=head1 CAVEATS
 
-sub mk_hash {
-    my ($me, $rest) = @_;
-
-    # $me is the hashref of cols/data from the immediate resultsource
-    # $rest is a deep hashref of all the data from the prefetched
-    # related sources.
-
-    # to avoid emtpy has_many rels contain one empty hashref
-    return undef if (not keys %$me);
-
-    my $def;
-
-    foreach (values %$me) {
-        if (defined $_) {
-            $def = 1;
-            last;
-        }
-    }
-    return undef unless $def;
-
-    return { %$me,
-        map {
-          ( $_ =>
-             ref($rest->{$_}[0]) eq 'ARRAY'
-                 ? [ grep defined, map mk_hash(@$_), @{$rest->{$_}} ]
-                 : mk_hash( @{$rest->{$_}} )
-          )
-        } keys %$rest
-    };
-}
+=over
 
-=head1 CAVEAT
+=item *
 
 This will not work for relationships that have been prefetched. Consider the
 following:
@@ -102,6 +116,8 @@ C<$first> will B<not> be a hashref, it will be a normal CD row since
 HashRefInflator only affects resultsets at inflation time, and prefetch causes
 relations to be inflated when the master C<$artist> row is inflated.
 
+=back
+
 =cut
 
 1;